Your doctor may not be the biggest fan of the coming electronic health care wave, but marrying mobile technologies with medical know-how has the potential to save lives, dramatically improve patient care, and slash significant costs, even in the poorest urban communities in the world, a new study finds. Researchers at the New Cities Foundation, a nonprofit organization in Paris that seeks to tackle the most intractable issues facing the world's fastest-growing cities, joined by a small team of health-care workers from Rio de Janeiro, recently concluded an 18-month trial in one of the poorest parts of the city, the favela of Santa Marta, a community of 8,000.